The invention relates to plastic piping. More particularly, the invention relates to preparation of plastic pipe/tube material for electro-fusion bonding.
In order to connect thermoplastic piping systems together via electro-fusion methods it is standard practice to remove the outer oxidized surface of the pipe to expose clean un-contaminated plastic. Typical previous methods rely on fixed or pivoting cutting tools and/or internal drive mandrels to remove the outer oxidized layers.
Examples of prior tools include those shown in U.S. Pat. Nos. 5,600,862, 6,434,776, and 6,698,321 and US patent application publications 2011232434A1 and 20150321260A1. A particular tool used with larger diameter pipe is the ROTARY PEELER RS by Georg Fischer Central Plastics of Shawnee, Okla., USA.
US patent application publication 20150321260A1 discusses problems of peeling out-of-round pipe. Smaller diameter pipe will acquire an oval shape due to coiling. Larger diameter pipe (e.g., shipped and stored in straight lengths) may acquire similar eccentricity due to stacking and handling
To ensure sufficient depth of peeling, it is known to pre-cut a witness score or groove in the outer diameter of the pipe. If the subsequent peel is of a depth smaller than that of the groove, the removed curl from the peeling will be discontinuous, terminating and then restarting each time the peeler blade reaches the groove. Thus, observing a continuous peel confirms that the peel is at least the depth of the witness groove.